High speed signaling poses significant challenges with respect to signal loss between an integrated circuit (IC) operable within a high frequency range and off-chip terminals, such as a dynamic random access memory (DRAM) interface, or an antenna for wireless applications. The cumulative path of a signal channel between the IC and off-chip signal origin/designation generally includes a package of the IC, and may further include an interposer on which the IC is affixed, and/or a board on which the IC or interposer is affixed. Interconnect routing for a given communication channel in the IC package, and/or interposer, and/or board responsible for carrying such high speed signals may employ a transmission line circuit for containing the electromagnetic wave as it is propagated. Such transmission lines are often in the form of a stripline, coplanar waveguide (CPW), or microstrip circuit.
Crosstalk between channels occurs when a signal transmitted on one channel of a transmission system creates an undesired effect in another channel and may be caused by one or more of capacitive, inductive, or conductive coupling between the channels. Interference between two channels as measured at an end of a path opposite from that of the transmitter is referred to as far end crosstalk (FEXT) and, assuming proper termination, is typically more problematic than near end crosstalk (NEXT) measured at the transmitter end of the path.
While transmission line designs can be more or less susceptible to crosstalk, as a function of path layout and geometries, overall channel crosstalk (particularly FEXT) remains a problem in high data bandwidth applications (e.g., exceeding 2.0 Gbyte/sec).